Linkage for equispacing radially guided apparatus



p 1948 R. w. JENNY 2,450,046

LINKAGE FOR EQUISPACING RADIALLY GUIDED APPARATUS Filed Dec. 8, 1945 INVENTOR;

Patented Sept. 28, 1948 LINKAGE FOR EQUISPACING RADIALLY GUIDED APPARATUS Robert W. Jenny,

to Curtiss-Wright' Corporation,

East Paterson, N. J., assignm- N. J., a corporation of Delaware Application December 8, 1945, Serial No. 633,655

6 Claims. 1

The invention relates to a mechanical movement of the circular motion type having general application to a set of relatively coaxially turnable arms designed, when any two arms of the set are relatively shifted to cause all of the arms of the set automatically to assume the same spacin angle. Specifically, the instant disclosure relates to a device for equi-distantly spacing the shlftable contact brushes of a potentiometer or rheostat of the kind having small overall dimensions due to the limited available space provided to accommodate them in some devices, like training devices for aviators, and therefore any controls for the brush carrying contacts of such instruments must be so small that the use of gears or like bulky members is impractical. On

the other hand, the electric requirements of such devices necessitate the use of a control which will set the contact brushes in accurately spaced apart relation and in definite prefixed location on their several resistances for each manual gross adjustment of the potentiometer controls. While such electric devices must necessarily be of a small overall dimension, still they are often used in apparatus like airships, aviator training simulating airships and likevehicles which are subjected to vibration, shocks and like rough usage which tend to damage delicate instruments.

Accordingly, the primary object of the invention is to provide a small, simple, compact and rugged mechanical movement for accurately, positively and automatically arranging the arms of a set or" coaxially mounted arms so that they will assume equal arc distances between adjacent pairs of the arms when any two arms of the set are moved to any acute angle.

Broadly, this objective is obtained by the arms of the linkage system resembling a toggle and arranged so that when any two arms are moved to assume any acute angle, all of the other pairs of adjacent arms will automatically assume such angled relation that the arc distances within adjacent arms are equal.

Various other objects and advantages of the innated clockwise as arms 18 I9 and 20. It is a re- 2 vention with the arms in an angularly related position.

In the drawing there is disclosed a plurality of superimposed dis-cs 10, three in the instant case mounted for rotary movement about a common axis II. This disclosure is intended simply to depict the least number of discs and associated arms which can be used to attain the objectives herein featured, Each disc in is provided with a radially extending bar l2 the outer end of which is enlarged to provide in the instant case a brush holder l3 which is provided with a pair of contact brushes [4 and 15 designed to contact respectively with the windings I6 and I] of a potentiometer for controlling electric circuits which in turn control certain indicators, motors, charting devices and other electric instruments now being used in an aviator training device. The rotatable units formed of the disks, bars and brush holders will be referred to hereafter as arms and desi quirement of these potentiometers that whenever an adjustment is made between two angularly related contacts the contacts associated therewith assume equal angles therebetween and thus subtend equal segments of the respective potentiometer. The present disclosure features mechanisms for automatically spacing the arms with pairs of the contacts when the end elements of the set are rotated in relatively separated relation.

This is attained by means of a form of linkage composed primarily of substantially straight, thin links arranged to be collapsed accordion fashion in a single plane and with the links disposed in pairs and arranged V-shaped between and conmeeting each pair of adjacent arms. For pivotally connecting the links to the arms the holders l3 are each provided with a pair of pivot pins 2| and 22 spread apart and disposed in the arc of a circle whose center is at the axis ll. For convenience of reference the links are numbered from right to left 23, 24, 25, 2B and the detailed description of the links connectin any adjacent vention will be in part obvious from an inspection of the accompanying drawings and in part will be more fully set forth in the following particular description of one form of mechanism embodying the invention, and the invention also consists in certain new and novel features of construction and combination of parts hereinafter set forth and claimed.

The accompanying drawing discloses a view in plan showinga preferred embodiment of the inpair of arms will be sufiicient to describe every other similar arrangement of arms linkage. The links are bent at their opposite ends in relatively opposite directions to form outer hooks 21 and inner hooks 28. The links are arranged one for each pivot pin and disposed with a hooked end 28 wrapped pivotally around its associated pin so as to form a pivotal connection therewith. The outer hooked ends 21 of each pair of links such as 23 and 24, are held in spaced relation with the ends curving away from each other to provide in effect a rolling motion with respect to each other.

It is suggested as being within the scope of the disclosure to provide the adjacent outer ends of the links with intermeshing gear teeth so that the motion of one of the links as it swings about its associated pivotpin will be communicated to its companion as if they. were geared together. However, an objection is raised to this suggested form of construction largely because the available space does not permit the utilization of gear trains for turning the links.

In the preferred form of the inventionherein disclosed the adjacent ends of the links are interconnected by outer connectors 30 which connect and form the crotch for the outer ends of the v arrangement of the links between the arms and inner connectors 3! which connect and 'form the crotch for the V arrangement of the two links,

like E i and 25, which are pivoted to the arm 19. These links are arranged so that the adjacent ends thereof are connected hingeably with the least possible space necessary to accommodate the connectors. In the form illustrated the connecto'rs are of Y-shaped design and are each formed of two strips of compartively thin metal with the stem forming portions 32 and 33 secured to their associate links by means of small rivets 34. In the illustrated form the connectors are illustrated as made of two pieces but it is within the scope of the disclosure to form the connectors with a V-shape by bending a single strip of material preferably of spring'metal. While these connectors are made of spring metal and biased at least weakly to cause the arm to collapse when released from restraint, it is'understood that the operation here featured is not dependent upon any spring action and the connectors, insofar as equi-spacing is concerned would function even if made of leather.

The operation is as follows assuming that one of the arms, such as the arm 2!! is held while the other end arm I8 is moved for instance counterclockwise in a separating direction. Tracing now the transmission of movement through the'lin'kage it will be seen that link 23-will swing about the pin 2I on arm IB, causing the outer end of the link '23 to swing downwardlyas viewed in the drawing. This will cause the upper end of link 23 to move counterclockwise pulling in a downward direction the next adjacent link '24 causing the same to turn clockwise about its "pivotal pin 22 on arm I9. The two links '23 and 24 thus turning about their associated pivot pins result in the separating of the arms I8 and I9 to the desired angle and considering the action at the outer crotch end'of the links '23 and '24 it will be seen that the opposing curved 'faces thereof in effect roll on the stem forming portion 32 of the connector 30 progressively with increase in angle between the arms I8 and It. At the same time that the link 24 is forced to turn clockwise about its associated pivot it will react at its inner end in a similar manner on link 25 outwardly in a counterclockwise direction thus forcing the outer end of the link 2'6 downwardly in swinging clockwise direction about its associated pin 22 on arm 23 thus causing the arms I?! and 20 to assume the same angular relation as was assumed by the arms I8 and [9. When the arms'ar'e equally spaced'it will be apparent that the angle between link 25 and the arm I9 for example, is equal to the angle between the arm I 9 and the link 2c. This-relationship is maintained by the rolling action of one link, when itsangular position'is changed, on the attached spring connector strip 3| tending to pull the other connector strip and its connected link along with it.

As a result the three arms I8, I9 and 20 illustrated assume equal angular distances therebetween, or diiferently expressed the angle formed by the arms I8 and 2B is bisected by the arm I9. It is appreciated that the illustrated structure may be duplicated adding additional arms and associated linkage, continuing the pattern illustrated until the desired number of arms to form the requisite set have been assembled.

By means of a device such as is hereindisclosed there is obtained a positive action between the several arms of the set; the connecting linkage isiof simple form with a minimum number of separate parts, and above all the construction facilitates a small compact assemblage of parts.

I claim:

'1. Mechanism comprising more than two coaxially mounted, angularly spaced and relatively turnable arms forming a set and means relatively turning said arms equal angular amounts on turning any two elements of the set relative to each other, said means comprising pairs of relatively turnable links for connecting each arm with the next adjacent arm, each link having at one end thereof a pivotal connection with its associated arm, the links of each pair disposed in V relation and the free ends of each pair of links being arranged for rolling movement relative to the other and each pair of links provided at its free ends with a connector hingedly connecting them together, "and the links pivotally connected to a common arm being similarly connected together,

2. A mechanical system comprising .a set of at least three elements mounted to turn about .a common axis, each element provided with apair of pivot pins with the pins spaced apart in the arc of a' circle whose center is :at said 'aXis, 'alplurality of links, one for each pin and of similar dimensions, arranged in pairs in V form'bridge'd between each adjacent pair of elements and each link provided with a curved end hooked about its associated pin to form a pivotal connection therewith and a plurality of similarV-shaped elements of "thin material, one for each pair of links and one for the linksconnected to the pins or 'a single element with its crotch portion located within the associated links and the leg portions of the V-shap'e'd elements secured to the links and hingedly' connecting the same.

3. A mechanical system comprising a set of more than two elements mounted for turning about 'a common axis, mechanism for automatically' spacing the elements into position with substantially the same :angular distance between each adjacent pairv of elements when the end elements of the set are rotated in relatively separated relation, said mechanism 'comprising'identical linkages between each adjacent pairs of the elements, each linkage being of V-form 'and comprisinga bifurcated spring connector having a free end of one of its legs connected to 'a link in turn pivotally connected to one of the elements and the free end of the other leg connected to another link in turn pivotally connected to the other element and the crotch portion of the connector spacing apart the adjacent ends of said links.

4. The device defined in claim 3 inwhich the connectors between each adjacent pair of elements and additional connectors secured to "adjoining links of adjacent linkages are disposed with their crotch forming portions alternately 5 disposed adjacent to and remote from said common axis.

5. In a mechanical system, the combination of three or more elements mounted to tum about a common axis and forming a set, linkage mechanism operately connecting the elements to space the same with equal angle distances between adjacent elements when any two of the elements are angularly adjusted relative to each other, said linkage comprising individual links arranged in zig-zag fashion with one end of each link pivoted to one of the elements, and spring connectors hingedly connecting in spread apart relation one end of each link with the contiguous end of the next adjacent link to form said zig-zag linkage so that an intermediate positioned element is pivotally connected to two spring connected links.

6. Mechanism comprising three or more arms mounted to turn about a common axis and a sys- 20 tem of linkage arranged accordion fashion connecting the arms, the links of the system arranged in pairs having a V form with the link ends forming the crotch of the V hingedly connected and with one link of a pair pivoted to one of the arms and the companion link of the pair pivoted to the next adjacent arm, the link ends pivotally connected to a common arm also being hingedly connected together.

ROBERT W. JENNY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,217,752 J andus Oct. 15, 1940 2,341,741 Putnam Feb. 15, 1944 

